perilous

1 of 2

adjective

per·​il·​ous ˈper-ə-ləs 

ˈpe-rə-

: full of or involving peril

a perilous journey

perilously adverb

perilousness noun

perilousness

2 of 2

noun

per·​il·​ous·​ness

plural -es

: the quality or state of being perilous

Synonyms of perilous

Adjective

• dangerous
• hazardous
• risky
• serious

Choose the Right Synonym for perilous

dangerous, hazardous, precarious, perilous, risky mean bringing or involving the chance of loss or injury.

dangerous applies to something that may cause harm or loss unless dealt with carefully.

soldiers on a dangerous mission

hazardous implies great and continuous risk of harm or failure.

claims that smoking is hazardous to your health

precarious suggests both insecurity and uncertainty.

earned a precarious living by gambling

perilous strongly implies the immediacy of danger.

perilous mountain roads

risky often applies to a known and accepted danger.

shied away from risky investments

Examples of perilous in a Sentence

Adjective

a perilous journey across the mountains

a perilous journey through hostile territory

Recent Examples on the Web

Adjective

The movie follows the team through perilous terrain, grueling physical challenges and interpersonal disagreements and friendships over the course of the nearly two-and-a-half month trek. — Angie Han, HollywoodReporter, 8 Sep. 2026

Not just any bill, but this year’s biggest in the state Legislature, dealing with catastrophic wildfires, arguably the state’s most perilous problem. — Los Angeles Times, 7 Sep. 2026

Why are certain people compelled toward any of these reckless, perilous, barely possible feats? — Guy Lodge, Variety, 5 Sep. 2026

Scientists previously created tiny diving suits for Madagascar hissing cockroaches that could be used in perilous search operations, according to a study published in the journal Nature Communications. — Devika Rao, TheWeek, 3 Sep. 2026

Word History

Etymology

Adjective

Middle English perilous, perelous, borrowed from Anglo-French perilleus, perillous, going back to Latin perīculōsus, from perīculum "test, risk, peril entry 1" + -ōsus -ous

First Known Use

Adjective

14th century, in the meaning defined above

Rhymes for perilous

• carolus
• garrulous
• querulous
• puberulous

Kids Definition

perilous

adjective

per·​il·​ous ˈper-ə-ləs 

: full of or involving peril

perilously adverb

perilousness noun